This invention relates to an improved furnace roof and, in particular, an improved roof for large scale molten material processing furnaces such as electric arc steel making furnaces and the like.
Modernization of the steel industry has resulted in, among other things, the introduction of new, lighter, water cooled roofs for electric arc furnaces which have considerably longer life than previous roof designs. These new water cooled roofs in some cases almost completely eliminate the necessity of thermal refractory linings, and their use has contributed considerable savings to the steel industry. Typical of these water-cooled roof systems are the roofs disclosed in U.S. Pat. No. 4,715,042 and co-pending U.S. patent application Ser. No. 165,609, filed Mar. 8, 1988, the disclosures of which are hereby incorporated by reference. Such water cooled roofs have largely been retrofitted to existing furnace systems and require hook-ups with externally located coolant circulation systems to supply water to and drain water from these roofs. The connection between the roof and the circulation system has generally been through flexible hose or the like which extend from the roof mast structure to the roof itself.
The roof mast structure in electric arc furnaces operates to reposition the roof relative to the underlying furnace and open the furnace top, for example, during initial loading or charging of scrap into the furnace, and at other times during or following furnace operation. The mast structure generally includes a post located adjacent to the furnace vessel upon which pivots a roof supporting structure. This supporting structure usually comprises arms extending out over the top of the furnace and downwardly extending chains or bars to which the roof itself is attached. The supporting structure is able to lift up the roof and swing it to the side or some other position to allow access to the open top of the furnace.
These pivoting mast and roof structures are generally made to swing the roof away from the furnace in only one direction, that is, as seen in a downward plan view, either clockwise or counterclockwise around the mast post. These clockwise and counterclockwise-opening furnace roofs are respectively known as "right-handed" and "left handed" furnace roofs because of the direction of swing opening the furnace relative to the mast post. Because the furnace roof may be opened during furnace operation or immediately afterwards, it is important that heat sensitive portions of the mast and roof structure exposed to the heat be adequately shielded, including the roof coolant connections. To avoid exposing the roof coolant connecting hoses to the extremely hot conditions of the furnace interior, the coolant inlet and outlet on the furnace roof and the associated connecting hoses are positioned so that they are opposite the side of the roof which swings over the open furnace. The hose connections are generally as close to the mast post as possible to minimize the length of hose and the possibility for interference. As viewed in a downward plan view of a typical furnace installation with the mast post at 6 o'clock, the left-handed roof configuration will have the coolant inlet and outlet connectors at approximately a 7 to 8 o'clock position, whereas the right-handed roof configuration will have the coolant inlet and outlets in approximately a 4 to 5 o'clock position.
Electric arc steel making installations will generally keep a backup or spare roof on hand for changeover during maintenance or emergencies. If a steel making installation has arc furnaces with both left- and right-handed roofs, there will have to be kept on hand both a left-handed and right-handed roof spare, even though the furnaces may be identical in other respects. Except for the location of coolant inlet and outlets on the furnace roof, only one spare might otherwise be required for backup purposes, at a considerable cost savings in direct expenditure and inventory costs.
Bearing in mind these and other considerations of the prior art, it is an object of the present invention to provide an improved roof for furnaces which may be utilized in both left-handed and right-handed furnace roof installations.
It is another object of the present invention to provide a combination left and right-handed furnace roof system which provides for water cooled roofs which are divided into different segments for coolant draining.
It is a further object of the present invention to provide a furnace roof system which eliminates the need for additional costly spare roofs in inventory to assure rapid changeover.
It is yet another object of the present invention to provide a furnace roof system which meets the aforestated objects in a simple and cost effective manner.